Previous studies have suggested that mossy cells are lost from the neuronal circuit of the dentate gyrus after various epiletogenic insults, and has given rise to the widely accepted, although often questioned, so called "dormant basket cell" hypothesis of epileptogenesis. In the previous award made to Dr. Soltesz he has set out to comprehensive challenge and explore at a cellular and synaptic level each element of the dentate-gyrus-hippocampal circuit to explore what elements are directly and indirectly impacted in a model of fluid percussion head trauma. This competitive renewal turns the focus of the study to the principal hilar neuron the "mossy cell" and proposes a rather straightforward set of experiments to disprove the "dormant basket cell hypothesis" and demonstrate that instead of being lost in models of epileptogenesis, significant numbers of mossy cells persist following percussive head trauma and contribute to an increased hyperexcitability by entering into a increased recurrent excitation of dentate gyrus granule cells which in turn feedback to both inhibitory interneurons and hilar mossy cells to increase hippocampal excitability and the resultant epileptogenic activity.